What do the clay minerals in the Chattanooga say?
Volcanic ash weathers into the clay mineral smectite (montmorillonite) (Berry and Mason, 1959, p. 509). Later alteration to a mixed layer illite-smectite composition occurs because of progressive burial, contact metamorphism, and hydrothermal alteration, among other mechanisms (Elliot, et al., 1991, p. 436). Bates and Strahl (1957, p. 1308) report an analysis of the clay mineralogy of a sample of the Chattanooga as mostly illite with some kaolinite present. No smectite was found. The clay mineralogy of the Chattanooga does not, therefore, lend support to Mr. Froede’s contention.
